[API] Adds core.monitoring.remote.RemoteProgressManager

and renamed core.monitor package to core.monitoring

Change-Id: Id6fd3d7dc425ed8c9c0068f0ff197de6d2cddf11
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1881
Tested-by: Jenkins CI
Reviewed-by: Holger Schmeisky <google@schmeisky.com>